Stroke, or brain attack as it is commonly called, can be caused by either vascular hemorrhage or vascular blockage with the latter accounting for about 80% of the events which lead to a stroke. Vascular hemorrhage is also termed a haemorrhagic stroke or an aneurism. Vascular blockage may also be termed ischaemic stroke. Both types of stroke are associated with considerable morbidity in terms of long-term neurological deficit and the risk of subsequent stroke as well as mortality post stroke.
Stroke treatment in the acute phase typically entails the invasive administration of clot dissolving drugs within the first three hours of the stroke as well as stabilization of cardiovascular functions and vital signs. After treatment in the acute phase, patients may typically follow four pathways: (i) in the case of mild stroke the patient may go home, (ii) in the case of a more severe stroke where it is believed an improvement in outcome can occur the patient may be sent to rehabilitation, (iii) other patients may be sent to special care/nursing home, (iv) some patients die. The present application is concerned with patients in the rehabilitation pathway. Rehabilitation is costly for health care systems hence it is desirable to provide improved patient outcomes at a lower cost where possible.
While the use of a blood thinning agent such as Tissue Plasminogen Activator may be used in the treatment of ischaemic stroke, it may be the wrong therapy to give in the case of a haemorrhagic stroke. Hence it is important to determine the type of stroke which has occurred in the patient. Furthermore, the drug therapy may vary during the course of treatment depending on the progress which the patient makes. Hence it is important to monitor the progress of the patient during treatment.
The application of nasal Continuous Positive Airway Pressure (“CPAP”) as a treatment for Obstructive Sleep Apnea (“OSA”) was invented by Sullivan and taught in U.S. Pat. No. 4,944,310. That patent described continuous positive airway pressure being applied to a patient, through the patient's nares, to treat breathing disorders, including sleep apnea. It has been found that the application of pressure which exceeds atmospheric pressure, typically in the range 4 to 15 centimeters of H2O is useful in treatment. OSA is an example of a broader class of breathing disorders generally referred to as Sleep Disordered Breathing (“SDB”).
In one form, nasal CPAP treatment of OSA involves the use of a computer controlled blower, such as the AUTOSET T™ device available from ResMed Ltd., to provide a supply of air or breathable gas at pressures in the range of 4 to 20 cm H2O to the airway of a patient via a mask. Examples of suitable nasal CPAP masks are the MIRAGE™ nasal mask and the MIRAGE™ full face mask also available from ResMed Ltd. The AUTOSET T™ device continuously monitors the state of the patient's airway and determines an appropriate pressure to treat the patient, increasing it or decreasing it as necessary. Some of the principles behind the operation of the AUTOSET T™ device are described in U.S. Pat. No. 5,704,345.
Another form of treatment for SDB is bi-level pressure support ventilation provided by way of a nasal CPAP mask. The treatment involves providing air at a higher pressure during the inspiratory portion of the breathing cycle and at a lower pressure during the expiratory portion of the breathing cycle. A suitable device for delivering bi-level nasal CPAP is the VPAP™ II ST/A available from ResMed Ltd.
A typical clinical pathway for OSA is as follows:                (i) A patient consults their general practitioner or physician;        (ii) The general practitioner or physician refers the patient to a specialist or a sleep clinic;        (iii) The specialist or clinic assesses the patient;        (iv) An overnight polysomnography is performed;        (v) An overnight titration study is performed.In a hospital setting, the team of physicians treating inpatients for other conditions may recognize symptoms of sleep disordered breathing on an ad hoc basis and refer the inpatient to a sleep specialist within the hospital. The patient will then proceed through steps (iii) to (v) as above.        
Recently it has become recognized that stroke patients may benefit from treatment with CPAP, for example as taught in International Patent Application WO98/51362 (Farrell & Pace). While the clinical pathways for identifying patients with OSA are becoming more established, there are few clinical pathways for identifying stroke patients who may benefit from such therapies. Furthermore, there are no known devices for managing the therapy of such patients.
It is an objective of the invention to provide methods and apparatus for managing the treatment of respiratory disorders in stroke patients. It is a further objective to provide methods and apparatus which assist in the identification or diagnosis of stroke patient condition to assist in treatment of the patient.